The invention relates to a system and method of blockage detection during an automatic adjustment of a movable vehicle part (window, tailgate, sliding door, side gullwing door, roof window, etc.) in a motor vehicle.
Current vehicles with an automatically opening or closing tailgate—as an example of a movable vehicle part—, on the control side, usually have an automatic control logic for the detection and prevention of a jamming or blocking event. For example, in this case, the rotational speed or the current of an electric motor as the drive for the adjustment is determined and monitored with respect to a sudden change of triggering thresholds. By means of correspondingly low triggering thresholds, a sensible and secure response behavior can be achieved in the event of a blockage and, as a result, the risk of injury in the pivoting range can be reduced to a minimum by stopping the electric motor (drive).
It is an object of the invention that, while the reduced risk of injury is maintained, nevertheless the availability of the automatic operation is to be increased when adjusting a movable vehicle part.
This and other objects are achieved in accordance with embodiments of the invention.
The blockage detection system according to the invention for detecting a blockage during an automatic adjustment of a movable vehicle part in a motor vehicle has an electric motor drive and an electronic control unit. The electronic control unit basically triggers the electric motor drive by way of a drive current such that a certain movement speed is reached. The electronic control unit detects and monitors the drive current as well as the movement speed of the drive. When the movement speed increases above a normal level, the control unit suppresses the detection of a blockage event if a drive current increase required for the movement speed increase cannot be determined. For the implementation of this blockage detection optimized according to the invention, the electronic control unit contains, for example, a correspondingly programmed software module.
The invention is based on the following considerations, recognitions and ideas.
For achieving a response behavior of the jamming or blockage detection that is as sensitive as possible, the triggering thresholds have to be selected to be correspondingly low. In certain cases, particularly in the case of an additional manual operation (such as a lifting by hand during the automatic opening operation), this results in supposedly detected jamming or blockage events. This is caused by the fact that, as a result of the additional manual lifting, for example, of a tailgate, the normally required drive current is reduced or the rotational speed (movement speed) is increased above the value of the purely automatic method. In contrast, a termination of the manual assistance, in turn, leads to a brief current rise or rotational speed drop. As a result of a thereby triggered blockage detection according to the state of the art, the actuators (electric-motor drive) are stopped and the automatic opening or closing operation of a vehicle part is thereby terminated. This may result in misunderstanding and annoyance based on the resulting limited availability of the automatic adjusting systems.
According to the invention, it is therefore provided to mutually link the drive current and motion speed signals (for example, the rotational speed signal) of the drive (for example, the electric motor) in an intelligent manner for plausibility monitoring as follows. By taking into account a rotational speed rising above a normal level, without the increased drive current demand actually required for this purpose, a manual assistance can be inferred in the same direction as the automatic adjusting direction of a vehicle part. The rotational speed drop or current rise occurring at the termination of the manual assistance can then be correspondingly ignored for a certain time window and/or a certain travel of the vehicle part.
Also, after a detected manual assistance for a certain time window and/or a certain travel, a reaction may take place only to a greater change of the movement speed and/or of the drive current, in order to continue to prevent the supposed detection of a blockage event.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.